With the development of communication technologies, transmission networks have evolved quickly from the era of Synchronous Digital Hierarchy (SDH) to the era of packet-based technologies. For packet-based technologies, a forwarding table is typically maintained at each network element, e.g. Ethernet, Multiple Protocol Label Switching (MPLS). A forwarding table for Ethernet is indexed by a Destination Address (DA) or by DA+VLAN-ID (Virtual Local Area Network Identification) in the case that a VLAN ID is present. Due to the discreteness of Media Access Control Layer (MAC) addresses, a hash algorithm is required to create and search the forwarding table. Whether the hash algorithm is superior or inferior depends upon selecting of a hash formula and adjusting of the size of the forwarding table. The algorithm is of a constant complexity in most cases, and of a relatively high complexity in the case of a failure in hitting, and may search throughout the forwarding table in a worst case. The label space of MPLS is 1M, and practically, not all labels will be used for a network element, so that in a system with limited memory, the hash algorithm can be equally used to create and search the forwarding table. The size of a hash table determines the efficiency of the hash algorithm, but adds to the overhead of the system. Such a mechanism has been used so far. Centralized data switching based upon a forwarding table for packets has direct influence upon the efficiency of data forwarding in a communication network and the complexity of system processing, which limits increasing of the switching capacity of a network element and raising of the throughput of a port.
In view of the above, an important approach for improving the efficiency of packet switching is to seek an appropriate method which can reduce the complexity of a searching algorithm for data packet forwarding to a constant value while not occupying too many system resources.
At present, there has been provided in the prior art a method and device for direct switching of frames containing destination information, as disclosed in publication No. CN 20050027881, which presents the following disclosure:                1) Information on egress ports of respective network elements, which have been passed, is stored in an Ethernet frame, and forwarding by each hop is based upon the information on egress ports, which is read from the data frame. In other words, this method does not require forwarding according to a MAC address. The information on egress ports can be encapsulated into a part of bits in the MAC address, thus forming a Local MAC Address (LMA). For a large Ethernet switch, a sub-domain can be used to represent an internal forwarding element.        2) Upon receipt of the Ethernet frame, an intermediate network element reads from the LMA an egress port to be processed by the present network element, and efficiently forwards the frame through the egress port without an access to a Forwarding Database (FDB).        3) Further more, a location processing server is also required, which stores and allocates IP and MAC addresses, and generates and resolves an LMA in response to a request of a local Address Resolution Protocol (ARP) within this local domain.        
However, the inventors have studied this solution and found that there are still the following drawbacks:                1) Due to limited bits available to Destination Addresses of a Media Access Control layer (MAC DAs), data frames can not be transmitted effectively in a large network, and if there are a large number of nodes, then an embedded routing table may exceed the number of available bits of MAC DAs.        2) It is difficult to determine the number of ports of network nodes because there may be thousands of ports present in a large Ethernet switch, which may also cause the embedded routing table to exceed the number of available bits of MAC DAs when being in use.        3) The generation of a local LMA is defined because an LMA is generated by the ARP protocol resolving an IP address, which involves no other implementation methods, such as self-learning of Layer-2 protocol Ethernet.        4) Neither application in a network nor intercommunication with a MAC forwarding mechanism for a conventional Ethernet switch has been involved.        